fryee



15 Sheets-Sheet I.

(No Model.)

B. M. PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887.

15 Sheets-Sheet 2.

{No Model.)

B. M. FRYER. CONSTRUCTION OF SHIPS.

NoQ 356,065.' Patented Jan 11, 1887.

IJVVEWTOR .ri ttorney WI T-N ESSES (No Model.) 15 sheets sheet 3. R. M; PRYER.

CONSTRUCTION OF SHIPS. No. 356,065. Patented Jan. 11, 1887.

Attorney (No Model.) 15 Sheets-Sheet 4.

R. M,PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887.,

(No Model.)

R. M. FRYER. CONSTRUCTION OF SHIPS. v No. 356,065. Patented Jan. 11, 1887.

Wa l macaw Ejvweukoc .15 Sheets-Sheet 5.

(No Model.) 15 Sheets-Sheet 6.

R; M; FRYER. CONSTRUCTION OF SHIPS.

' No. 356,065. Patented Jan. 11, 188'7.-

' lic'yfa.

r "M u d d Z d HIM T'I W 3, Pig; My fl 'i m. a In; I

I. .II M HH JIhI I If,

6 I if" I 1 d m. m. d |11+ a a, I

WITNESSES I .dttorney 15 Sheets-Sheet 7.

(No Model.)

R. M. FRYER. CONSTRUCTION OF SHIPS.

Patented Jan. 11,1887.

G Q G G Q 0 O 0 FM n Y flttorney (No Model.) 15 SheetsShe'eu 8.

R. M. PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887.

Kay'- 10.

(No Model.) 15 Sheets-Sheet 9.

R. M. FRYER.

CONSTRUCTION OF SHIPS.

N0.-356,065. Patented Jan. 11, 188 7.

1 IL. I

15 SheetsSheet 10.

(N6 Model.)

B. M. PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887.

s w .5 .w

No Model.) 15 SheetsSheet 11.

- R. M. PRYER.

CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887.

(No Model.) 15 SheetsSheet-12. R. M. PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11,1887.

AHHW W H m I Hm.

" llm. M

(No ModeL) 15 Sheets-Sheet 13.

R. M. PRYER.

CONSTRUCTION OF SHIPS. No. 356,065 Patented Jan. 11, 1887.

(No Model.) 15 Sh'eets-Sheet 14.

R. M. FRYER.

CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11,1887.

In '03 a??? Masses,"

(No Model.) 15 Sheefs-8heet 15. RM. PRYER. CONSTRUCTION OF SHIPS.

No. 356,065. Patented Jan. 11, 1887;

WI TJV ESSE Attorney me "miss aoenar 1n. Furnace BROOKLYN, NEW ong,

CONSTRUCTION OF- SHIPS.

SPECIFICATION-forming art of Letters P atnt No. 356,065, dated January 11, 18:47. Application filed 1 \'ovemb r 17,1886. set-nil No. 219,114. (N6 model.)

To all whom it may con/corn.- Be it known that I, ROBERT M. FRyEma citizen of the United States, and resident of the city of Brooklyn. county'ofl-Kingsyand State'ot' New York, have invented certain new antLusefulIniproveinents in the Construction of Iron Ships-of which the'followingis a specification.

My invention relates to tlie coiist'i' nctioh of zo ironeships, and the principal objects sought to be attained are simplicity and economy in constructionythe production of a vessel which shall be absolutely fire-proof and practically non-sinlr'able, and which shall possessin the highest degree the requisites of solidity, rigidity and ability to resist shocks anhstrainst to so dispose the weight of material, the ma chiner y, and the necessary supplies as to make the vessel self-ballasting; to providemeans'for asily handling and controlling thc vesselat seaand in port; and-to provide or the health,

convenience,comfort, and safety of both passengers and crew.

. To ,these endsthe invention'consists in the construction hereinafter fully described and claimed.

In the accompanying dra'win'gs vhich form part of this specification, Figure 1 represents.

a perspective view of a'shi'p constrnctetlaccording to n y invention; with-aportion of the upper deck removed. Fig. 2 represents aeentral vertical longitudinal section. P Fig.1? rep-J represents one of the transverse plates and a port'ionofthe outside sheathing or hull in perspective; Fig. 8jreprcsents a transverse section through the ship in rear of the engineroom, showing two of the 'boilersin' e'nl elevation. Fig. Sis a similarsection taken'im niediately in front of the engine,'and looking toward thestern. Fig. '10 represents a vertical longitudinal section through a part-of the vessel, the section being taken through one of saloon, and Fig; 5 a similar sectionini' the-hoilertunnels, andshowing two hoilers in sine elevation. Fig.1l represents a siniilar.

section thro'nghthe engine-room fon the line 11 11 Fig.9, the engine beingsliown in elevation, with parts broken away; Fig. 12 rep resents. a perspective view ot'lthe stern of the vessel. Fig. 13 represents a vertical, transverse sect-ion .on'the line 1313, Fig. 2;-looking toward the stern. Fig. 14 represents 'a verticaljsection atright angles to that'showirin" Fig. 13,"and taken on th'eline 14. Fig. 15

vrepresents afhorizontal sectiontakeu on.the

plane of the line 15 15,.Fi g's. Z-and Fig. '16 'repfesents the keel ot' the vessel in side elevation,the ccntratpo'rt'ion and one of the resentsavertical section through one 0t the Stairways; and Figs; 18 and represent, ref spectivel'y'in. elevation, and vin section, one of the hearings of the shaitof tliev'esfseh.thelatte'r figure showing alsolaportionof theor sing ortnhe whieh'surronnds the shaft.

With theexcepti'on of the keel and the bearain'gs and fittings of theshaft and engine the this-invention is formed 0troll'edplate' iron .01 steel, which is the simplestp'roductof the rolling mill, and which. is produced by the ordinary rolls with which every mill is proviiied;

. 7-5 entire structure which forms the subjeetotl thus avoiding-the use of speeialmaehinery for the productio'n of any partofthe hullor firame of the vessel, and even the keel may bc mad'e entirely'of'metal plates, as will .be hereinafter explained.

Instead ;of

. i J 5 the ordinery rihs of ironvessels,

asheretofo re constructed I'ern ploy i'ron plates,

which are erected on and secured to the keel, and which correspond in size and shape with the cross-section of the vessel at the points at."

which they are erected. These plates are ereotedat-intervals' which correspond with the length of thestate-rooms or other compartments into which the vessel is to-be divided,-

and form the'partitionsor walls between such rooms or compartments,'thus effectually separating the latter. The plates are cut out to,

form the'various passages and longitudinal compartments which extend entirely or partially thro'nghlthevesseli The-walls of these passagesor' compartments are formed of iron plates which extengl'thronghout their length,

plates.

and are secured to the edges of the openings, thus connecting all the plates through which the passages or compartments extend.

The decks are composed of iron plates of sutficient thickness to give the required strength. The upper deck rests upon the tops of'theiron plates, which I denominate section-plates, and are secured to all of them. The other decks are composed of plates ofsufficientlength to extend entirely across the vessel, and of a width to fill the spaces between the section- They' rest upon and are secured to angle-irons which are riveted to the plates.

Inasmuch as the plates whichitake the place of the ordinaryribs extend entirely across the vessel, it follows that any shock, strain, or pressure to which the vessel may be subjected will be resisted by the entire plate, and that one side cannotbe stove in without displacing the whole plate and breaking the opposite side of the vessel out; nor can the vessel be collapsed except by the application of pressnre sufiicient to double up the plates between the points between which it is applied; but the plates being all connected by the decks and the walls of all thev'arious passages and coinpartmenls, this doubling up or bending is resisted by all the plates throughout the ves-' sel, so that any crushing force applied at any point is taken up and resisted by th'e whole structure. I

The interior of the \essel, outside of the various passages and occupied apartments, is divided into a great number of air and water tight compartments; and even the passages and occupied apartments are provided with doors which are fitted to close air and water tight, so that in case of -accidentsuch as the breaking of one or more holes through the hull-the injured section of the vessel can be entirely andcompletcl y shut off from the uninjured parts, so that water can only enter into the compartment or com partmcnts broken into, whereby the buoyancy of the vessel will not be materially impaired. It has been asserted, and undoubtedly with truth, that thebreaking of propeller-shafts, which is a frequent occurrence, is due not alone to torsional strain, but to the combined. torsional and lateral strain which results from what may be termed the flexibility of the vessel. Now, in order to guard against shaft-breaking, it becomes necessary to stiffen and strengthen the hull suilicicntly to remove or overcome this flexibility; and this is one of the objects of my invention, which I claim to have accomplished in the construction hereinafter more minutely described.

,fiy my construction I am enabled to place the engine, the boilcrs','and other machinery nearer the bottom of the vessel, where they will serve as ballast, thus avoiding at least the use of the ballast necessary to balance these parts when placed in the upper part of the vessel, and to that extent saving room for more valuable cargo.

In carrying out my ihvention I first construct the keel, which is shown in Fig. 16,-and

It is formed of is designated by the letter A. a series (preferably three) of longitudinalbars or ribs, a a a, and two side plates, a at, the whole bolt'edor riveted together, as indicated in the drawings. Theribs a act may be made of solid bars, or of plates of iron placed together flatwise and riveted. ,It being imprac-v ticable to make the, bars and plates integral.

through their length-,rthey' are made in convenient sections, which are bolted or-riveted together. the joints being so disposed as to break or lap each. other.

twice as wide at the stern as at the bow. The

bars a a are flush with the upper and lower edges, respectively, and the bar a is .disposed between the two,- running parallel with the bar a and joining the bar at" at its front end.

In order to still further strengthen the keel in its vertical plane, iron-girders or I beams at are placed between the bars a a a", as'represented in Fig. 7", the-lower ones being tapered to adapt them to the space between the bars a a Along the sides of the keel opposite the bar a are longitudinal angle-bars a'Zwhich are secured in place by bolts or rivets passing entirely through all the parts. The purpose of these anglebai's will be hereinafter indicated.

On thiskcel are erected. at suitable intervals say of seven and a half fcetwhat'I' denominate section-plates. (Shown in elevation in Figs. 6 and 7, and in perspective in Fig. 7,- and marked B in all the figures.) Thcse'are lnadei'rom plate-iron of suitable thickness and strength, and of asize and shape to correspond with the cross-section of the ship at the points at which they are placed. These plates are The keel tapers throughout its length, being nearly angle-irons, to which in turn are riveted the I outside sheathing which constitutes thehull of the vessel, and the plates which form the walls of the various passages and compartments. The angle-iron which surrounds the notch 11 is riveted or bolted 'to the keel, and forms the fastening which fastens the keel and the platcsB together. Similar angle-irons also extend transversely across the plates to support the lower decks,-these' latter also being securely riveted. the structure thus far described are securely fastened together, and each forms a brace or stay to support the adjacent or contiguous parts, forming a substantial structure capable of withstanding and resisting strain from all directions.

Thus all the parts of I The section-plates B,whi ch occupy the central or engine section of the vessel, 'are out out,

as shown in Figs. 6, 7, 7, and ,9. y

The opening 1) represents the niainsaloon, which extends through the entire length of the vessel, as represented in Fig. 3.

The openings b 'represent the lower saloon, which is divided through the engine-section" ofthe vessel by the central portion of the plates Bavhich constitute the frame of the 'engine, but which forward and aft of the enginesection occupies a central position .directly under the main saloon, the plates, except those which form the frame of the engine, being cut out centrally, as represented in Fig. 8. n

The openings (2 forward and aftof the engine-section form the tunnels in which the boilers are located; butin the enginesection they form' a pa'rtof the engine-room, which extends entirely across. Thelower portions, d of theopenings d form the ash-tunnels'which receive the ashes fromthe furnaces. The opening I)", Fig. 6, forms a passage for the propeller-shaft. from the engine-room to the stern, and forwardofthe engine'room forms a tunnel or passageway. The upper side portions of the plates B form the partitions between the. state-rooms, the

length of which is regulated by the distance the plates are placed apart. The dividing walls between the state-rooms and the'saloons theflanges surrounding the openings inthe plates B. c r Any or all of the partitions between the staterooms may be cut out in order to connect tWO or morerooms, and, i-f-provided with doors, the rooms maybe separated or thrown into communication at pleasure. I I

The lower part ofthe ship is divided into numerous air-tight compartments, as shown in Figs. 8 and 9, where they are designated by the letter c. These compartments are all to be connected with an air-forcing apparatus,

(not shown,) which is to be operated by the engine, and are to be filled with compressed air under a pressure as great or greater than that of the-water against the outside of the vessel, in order thatrif a hole be broken into any compartment through the side or shell ofthe vessel water may be prevented from en- -tering.

.Di' course it'the opening be formed at or near the top of any compartment the contained air, by reason of its being lighter than water, would, in the absence of any provision against such a contingency, escape, and water would enter to the height of the opening; but in order to guard against this each compartment is divided by a diaphragm or partition, 0, arranged in the plane of the outside shell and a short distance from the latter, such diaphragm or partition being connected at the top and sides with'the walls of the compartment, and wholly or partially disconnected at the bottom. Thus if an openingbe formed at the top only the space between the diaphragm and the hull of the vessel can fill with water, theairin the inner divisionof the compartment being prevented fronresc'aping bytheweight and pressure of the wateri-n the outer division, and the water beingprevented by the pressure of the a-ir'from entering,

Each compartment 0' has an opening through I its innerwall'; through which entrance may be effected from the passages or occupied apart ments when desired, and'these openings are all provided with doors or man-hole covers S,

adapted to be closed air and water tight. t

I" propose to use in this vessel the-engine patented to me by LettersPatent of the United States, dated August 21', '1883, and'numbered 283,704, which. is admirably adapted to this purpose. This engine, which in the drawings isiharked 0,.ie located ngnidships in the bottom of thevessel, and rests, on the keel. The:

bearings-for its shaft are formed in or. attached to the plates B,-tis indicated at b, thusin reality makingthe enginea part-of the ship. The engine is of. the compound t .pe, being composedof a high-pressure cylinder, G, and a" low-pressure cylinder, 0'. These are so'propo'rti oned thatthe first occupies and fills the.

space between two ofthe division-plates B, and the latter a double space, for the accom' modation ofwhich that part of the intermediate plate between the dotted lines 00-31, Fig.

f7, is out out, as indicated in Fig. 11. The enare formed of iron. plates, which are riveted to {ti-re engine being thus confined tothe bottom ,of'the'vessel, not only serves as ballast, but displaces the ballast necessary to balance the cylinders and conneotionswhen the latter are located in the upper part of the vessel. The

boilers'D are also locatedin t-hebottomof thevessel in tunnels or passages d at either side of the keel.

In Fig. 51 show twenty boilers arranged in pairs forward and back'ofthe engine-room. The boilers may thus be said to be arranged in four groups,two forward of the engine-- room andtwo back of thesame. f

.The furnaces are connected byfiues d with horizontal fines d at the. sides of the vessel, which fluesd connect with the stacks, six of which, areshown in Fig. 1three at either side of the vessel. By means of valves or damp- Ils ers suitably disposed in the fines d any one' or more of the furnaces may be out off when not in use. l

The boilers an d furnaccs'adj acent to the engine-room are sufficiently removedfrom the latter to form fire-rooms d", and the pairs of boilers and furnaces are sufficiently separated to form similar rooms between thesame.

In order to provide for the comfort of the firemen, a shield, d, is placed in front of each boiler, a short distance therefrom, the top of the furnace and the grate extending to said shield, the latter having'an opening through which thefurnace is fed, thefurnacerdoors being arranged to close said opening. I The shield (1 extends fromthe floor to withina short tance of the top of the room,and entirely across the latter, the a 3'.- to support combustion being thrown off by radiation from the shield d, and

this is immediately drawn off to supply the furnace, its place being taken by afresh supply,which-is-admitted through a fine or opening at any convenient part of the room.

' Below the boiler-tunnels are longitudinal tunnels d, into which the ashes from the furnacesare discharged through openings (Z and from which they are removed by any suitable machinery. c

The boilers are mounted upon trucks which run on tracks in the boiler-tunnels. This is for the purpose of facilitating the removal of the boilers when for any reason it is desired to shift them or take theinout of the tunnels.

In order to provide for the removal of the boilers from or their introduction into the vessel, suitable hatchways are formed, preferably above the engine-room. Then by breaking the connections the boilers may be run along on their tracks until the one which is to be removed is brought into proper position in the engine room. whenit is hoisted through the hatchway to the-deck. p

In order to provide for the shifting and re moval of the boilers, the domes of the latter are made separable, so that the connections may be broken by simply disconnecting them from the boilers. When the latter are 'removed, the domes are left in position, and- When the boilers are replaced are again attached. 1

Making the domes of the boilers separable I believe to be a novel feature, which I reserve for another application, it being referred to here simply to show how the boilers may be separated from their connections preparatory to their'renioval from the vessel. 'The opening 1) represents the coal-bunkers, which are located between the boiler-tunnels forward and aft of the engine-room, as shown inFigs. 2.and 5. The fioorsof these bunkers are somewhat higher than the floors of the boiler-tunnels, and their inner walls have openings b,-'through which the coaltender passes the coal into thefire room. The openings are provided with doors,-which may be tightly closed.

The shaft of the vessel passes through the "openings 2) in the section-plates B, immediately above the keel. These openings are large enough to permit the shaft to be passed in freely from the stern. The boxes or bearings for the shaft are attached to the plates B, and these latter resting upon the keel give to the shaftthroughout its length afirm support. The bearings consist of, first, heavy iron rings b b, riveted or bolted to the plates onoppositesides, and, second, theboxes proper, which are placed within the rings b. These boxes are formed of segmental parts I); which are grooved on their outer surfaces, so as to fit within and overlap the rings b", as shown in section in Fig. 19. They are also channeled on the inner faces to receive and hold Babbitt metal, to form anti-frietion bearing-surfaces, as usnal'in shaft or journal bearings.

The segmental sections are made thinner toward their lowerends, so as tomake the bearing-surface eccentric to the inner circumference of the supporting-rings I), as shown in Fig. 18, and whenin' position donot'entirely surround the shaft. This is for the purpose of permitting them to be accurately "adjusted to theshaft in the event of the rings 1) not being exactly in line. The adj ustmentis effected by driving wedges bhbetween one or. more of the joints. A tube, 1), surrounds the shaft between the thrust -bearing, (not 'shown,) which is located near the main bearing b",'atthe inner end of the shaft, and the outer bearing adjacent to the screw. This tube b is forinedin sections, which fit between the section-plates B and upon the rings b, the'joints being seen rel y packed to prevent the escape of the oil, or oil and water, which the tube is designed to contain as a lnbri cant for the shaft-bearings.-

I The end of the shaft back of the screw is supported by a hanger, b which contains an adjustable box, such as above described. This hanger depends fromthe stern of the vessel, and is entirely disconnected from the keel and the rudder-stanchion, so that if these parts be injured or entirely broken awaythe support for the end of the shalt may be left intact.

In the bow of the vessel is a transverse passage, G, opening through both sides ofthevessel, in which is located one or more screws, by,

which the bow maybe thrown around in either direction, and which may be used as an auxiliary steering apparatus, or in the event of the rudders being disabled or carried away may take its place altogether. This screw, which in the drawings is marked E, is driven by a sep arate engine, F, of the character of that for which Letters Patent of the United States were granted to me on the 19th day of March, 1872, and numbered 124,805. This engine is connectcd with the boilers I), bywhich the main engine of the vessel is driven. An arnnf, of the engine works through an opening in the top of the passage G, and is connected with the crank of the shaft which carries the screw or screws E. The shaft is supported by transverse bars 6 a, between which the crank works.

later is prevented from entering the vessel through the opening through which the armf works by a vertical tube, 9, which rises from the tube whichforms the transverse passage G, which tube 9' extends above the water-line of the vessel.

The screw E, when used in the larger class of vessels, must necessarily be quite large say ten feet indiamcier iu order to exert the requisite force, and it is evident that an opening to acconnnoda'te such a screwwould materially retard the progress of the vessel by often ing'a large resisting-surface, and 1 therefore in front of their bers 9?.

ure, jare tanks-1 or reservoirs I, for 'waten which-tanks are connected pipes or passages, 1', (shown in Fig. 13,) with the; cylinders H.

E is not inuser These gates are operated and moved by hydraulicpressure, as follows:

Within-the vessel, and a sufficient distance back. from the opening'fG, are cylinders H, (Tone at eachsida) the connected by piston-rods h with bosses or pro-1 gections gion the inner faces of the gates g, and betweenthe mouthsot the passage G and thecylinde'rs Hj-are chambers g into which the gates g are drawn to open the passage G. I In the upper part of'the vessel, at-a suflicient elevationto' give the requisite press containing by suitable v The gates g" beingclosed, and it being desired to open them, water is admitted from the tanks I to thecylinders II, I pistons h, when the latter are moved back,drawing the gatesinto their cham- The reverse movementto close the gates is efifecte d by cutting off the water from the front of the. cylinderv and admitting it .throughanother pipein 'rear of the piston 71. The cylinder is provided at each end with an outlet, h through which the water admitted to move the piston in one direction escapes as the piston is moved in theopposite direction by a fresh supply admitted at the other end.

It is of course to be understood that both the outlet and inlet pipes are provided with suitable cocks by which the water may be turncdon or ofi' at pleasure.

The gates g to receive movable disks g which fit the openings in the hull of the vessel, and which are adapted to be moved out into said openings tobring their outer faces flush with the hull, to form a smooth exterior. They are also operated by hydraulic pressu through the following instrum'entalities: The

' piston-rods h, whichare connected with the inders H into chambers H slidinggates g, are hollow, and communicate, through openings or passages g, with'the chamber of the gates 9'. They extend, when the gates'are closed, entirely through the cyl- V in rear of the cylinders H, which chambers H are of sufficient length to receivethe portions of the pistonrodsin rear of thepistons 11. The reservoirs I, 'or other similar reservoirs above the waterline, are connected with the chambers H by suitable" pipes or passages, 76", also. provided with stop-cocks NVhen the latter are opened, water is admitted, through the piston-rods h, to the chambers of the gates g in rear of the movable plates 57, and the pressure of the waable outlets, whenthe pressure of water against.

ter thus applied being greater than the pressure of the water against the-outside'the plates. will beforced out into the openings in the hull,

exterior surface, as above explained.

When it is desired to open the gates, the

and the latter will be closed, forming a smooth reservoirs are out off by turning the cooks in the connecting-pipes, and the water in rear of the plates is allowed to escape through suitre, which is applied pistons hot which are are recessed on their outer faces the latter are free to be moved back, as above explained. Y

- In the stern of the vessel- I form a chamber, 'K, which extendsentirely across, and has openings K through the sides of the vessel, immediately above the water-line. The walls 'Of this chamber are connected at their ends to the sides of the vessel, and intermediatelyare supported by the section-plates B, which divide the vesseltransversely, thus making of alife or other boat or boats, which are carried therein till required, when they are discharged-through the side openings. Access may be had to this chamber from the interior of the vessel, and the occupants may enter the boats before they are launched, thus-insuring I both safety and comfort.

.In order that the state-rooms, any or all, may ,be provided with closets, urinals, and permanent wash-stands, I provide sewer or outlet pipes L,-wit-h which these fixtures may be connected. These pipes I preferablylocate at the sides of the vessel, running them through the flues d, as shown in Fig. 8, where they will be entirely out of the way. They are open at both ends, so that when the vessel is in motion a current will be induced through them, which will carry off deposits and keep them clear andclean.

In order to prevent the flooding of the sa-. Icons in theevent of a sea breaking over the vessel while the hatches are open, the stairs which connect the several decks are thickly perforated, as represented in Fig. 17, to allow the water to run through, and under each stairway is a tank, M, which, receives the water as it runs through the perforations, and from which it may be pumped or discharged through avalved outlet, Z, which leads through the side of the vessel.

- All the doors of the variousapartments and compartmentsareto be fitted to close. air-and .the walls of the chamber an integral part of the "essel. This chamber is for the reception water tight, so that any part of the vessel may be eifectuallycut 0d and separated in case of accident or necessity. Thusin casc'of injury to the hull the injured part may be separated fromjthe remainderof the vessel; or, in the event of fire breaking out within the vessel, by-closi ng the doors of the apartment in which it originates, it may be confined to such apart ment and extinguished by the introduction,

with double doors, one of which is to be hung on hinges,as usual, and the other of which will be arranged to slide in a frame, (see Fig. 10,)

and will be fitted with rubber or leather gaskets, to adapt it to be closed air-tight in case of emergency. These sliding doors, which in the drawings are marked 0, are to be made of steel, so as to possess sufficient strength with 

